The present invention relates to systems where radio telephones (son units) and radio controllers (father units) to each of which radio telephones are connectable wherein the radio telephones and the radio controller are not bound to a one-to-relationship, more particularly the present invention relates to an exchange which controls the radio telephones and the radio controllers in a functionally combined system, and methods of delivery of control signals between the respective radio telephones, radio controller and exchange.
JP-A-2-94827 discloses the relationship between conventional mobile terminal control units (radio controllers) and mobile units (radio telephones). The conventional technique of JP-A-2-94827 discloses registration of information of the positions of mobile terminals when radio zones corresponding to mobile terminal control units are disposed in overlapping relationship. In order to prevent a deterioration in the quality of telephonic communication caused by mutual modulation due to transmission or reception, the conventional technique compares the reception level of a position reporting signal from a registered radio controller and that of a position reporting signal from another radio controller and, when the latter is higher by a predetermined value or more than the former, the radio controller to which the positions of radio telephones are registered is changed from the former radio controller to the latter one.
Although the conventional technique can determine whether a radio telephone is in the radio zone which its radio controller has, by registration of the position of that radio telephone in the radio controller, it cannot determine the distance between the radio controller and that radio telephone and the azimuth of that radio telephone and hence the precise position of that radio telephone. That is, the conventional technique cannot grasp the behavior of a person having a radio telephone. For example, in a building, it cannot determine whether that person is in a meeting room, a lounge or moving, or cannot determine the portion of a floor where he is. Thus, the conventional technique cannot connect a call to him or page him in a manner suitable for the place where he is.
Since in the conventional technique the condition of movement of each of the radio telephones cannot be grasped, the behavior of a person having the radio telephone cannot be predicted or it cannot be checked whether the behavior of that person is in a predetermined course of action.
Since the conventional techniques have no displays which each display the positions of radio telephones visually and hence no transmission/reception of signals between the radio controller, an exchange and the display is considered, it is difficult to understand the behavior of a person having a radio telephone.